* {
  margin: 0;
  padding: 0;
  list-style: none;
  user-select: none;
}
#app {
  margin: 50px auto;
  display: flex;
  justify-content: center;
  align-items: center;
}
#app .box {
  height: 200px;
  position: relative;
}
#app .box ul {
  display: flex;
  justify-content: center;
  align-items: center;
  margin: 0 auto;
  background-color: #ccc;
}
#app .box ul li {
  width: 235px;
  height: 30px;
  line-height: 30px;
  cursor: pointer;
  padding: 5px 0;
  text-align: center;
}
#app .box ul .active {
  color: #fff;
  background-color: #980d0d;
}
#app .box .detail {
  position: absolute;
  left: 0;
  top: 40px;
  height: 360px;
  width: 700px;
  background-color: yellow;
}
#app .box .detail div {
  height: 360px;
  width: 700px;
  text-align: center;
}
#app .box .detail div:nth-child(1) {
  background-color: yellow;
  display: none;
}
#app .box .detail div:nth-child(2) {
  background-color: #00ccff;
  display: none;
}
#app .box .detail div:nth-child(1) {
  background-color: #bfa;
  display: none;
}
#app .box .detail div .active {
  display: block;
}
#app .box .btn {
  position: absolute;
  bottom: -190px;
  left: 50%;
  transform: translateX(-50%);
}
#app .box .btn span {
  width: 50px;
  height: 30px;
  line-height: 30px;
  background-color: #fff;
  text-align: center;
  font-size: 14px;
  padding: 10px;
  cursor: pointer;
}
#app .box .btn span:hover {
  background-color: #ccc;
}
